1. Field of the Invention
The present invention relates to respiratory interface devices for transporting a gas to and/or from an airway of a user which include, but are not limited to, a patient interface device and a support assembly and, in particular, to a respiratory interface devices wherein the patient interface device is floatably coupled to a support assembly.
2. Description of the Related Art
There are numerous situations where it is necessary or desirable to deliver a flow of breathing gas non-invasively to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheal tube into the patient's esophagus. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation. It is also known to deliver positive airway pressure (PAP) therapy to treat certain medical disorders, the most notable of which is OSA. Known PAP therapies include continuous positive airway pressure (CPAP), wherein a constant positive pressure is provided to the airway of the patient in order to split open the patient's airway, and variable airway pressure, wherein the pressure provided to the airway of the patient is varied with the patient's respiratory cycle. Such therapies are typically provided to the patient at night while the patient is sleeping.
Non-invasive ventilation and pressure support therapies as just described involve the placement of a patient interface device such as, but not limited to, a mask component having a soft, flexible sealing cushion on the face of a patient. The respiratory interface device component may be, without limitation, a nasal mask that covers the patient's nose, a nasal/oral mask that covers the patient's nose and mouth, or a full face mask that covers the patient's face. While any type patient interface device may be used, the following description shall use a nasal mask as an example. Such patient interface devices may also employ other patient contacting components, such as a support assembly including a frame with forehead supports, cheek pads or chin pads. The patient interface device is connected to a gas delivery tube or conduit and interfaces the ventilator or pressure support device with the airway of the patient, so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient.
One requisite of many of these respiratory interface devices, particularly medical respiratory interface devices, is that they provide an effective fit against the user's face and that the respiratory interface device contours with the user's face to limit or prevent leakage of the gas being supplied. The fit of a respiratory interface device is partially controlled by the interaction between the patient interface device and the support assembly. That is, a support assembly may include a rigid frame and a number of support members, such as, but not limited to, straps. The patient interface device is coupled to the frame. The support members are coupled to the frame and extend about the user's head.
This configuration positions the patient interface device to cover the user's nose and provides an effective fit against the user's face. This fit, however, may be effected when the user moves during sleep. That is, for example, a user may roll their head to the side while asleep. When the frame contacts a pillow or mattress, the frame may shift relative to the user's face and disturb the fit of the patient interface device. More specifically, the patient interface device is coupled to the frame in such a manner that the patient interface device moves with the frame. Thus, when the frame shifts relative to the user's face, the patient interface device shifts relative to the user's face.
One improvement to this configuration incorporated a flexible coupling, such as, but not limited to, a multi-pleated bellows, between the frame and the patient interface device cushion. That is, the patient interface device includes a cushion that engages the user's face and creates a seal. The flexible couplings allowed the cushion to remain substantially in the same position relative to the user's face even if the frame were to shift relative to the user's face. The disadvantage was that the flexible couplings occupied a space about the same size as the cushion. In this configuration, the frame that accommodated both the cushion and the flexible couplings could be found to be uncomfortable and unwieldy. Further, the flexible couplings, along with the rest of the patient interface device, needed to be cleaned and the folds of the flexible couplings made cleaning difficult.